In my quest to find a suitable diagram for the heart, this is what I found:
Definitely use your textbook as a guide on this. It only takes a google search to realise the ridiculous number of variations of diagrams for the heart and different annotations.
The heart contains two atria, two ventricles, the septa, AV-valves (tricuspid and bicuspid), chordae tendinae and papillary muscles. Septa describe the dividing walls between the right and left atria and ventricles respectively.
The chordae tendinae a.k.a. heart strings, are attached to the papillary muscles which prevent the walls collapsing onto themselves during…